OBJECTIVES: 1) Isolate and characterize feline oncornavirus-associated cell membrane antigen (FOCMA). FOCMA will be isolated by using polyacrylamide gels and triton X-100 extraction. Competitive cytotoxicity will be used for in vitro detection of FOCMA. 2) Study the role of FOCMA as an immunogen in the prevention of neoplasms in cats. Antibodies to FOCMA are known to be tumor protective in cats that have recovered from feline oncornavirus infections. There is evidence that FOCMA antigens are present in FeLV and non-FeLV induced neoplasms of cats. Similar molecular weight proteins have been isolated from the cell membranes of avian and rodent tumors and these antigens are protective against oncornavirus and chemically induced neoplasms. Cats will be vaccinated with FOCMA antigen(s) to determine its efficiency as an immunoprevention of cancer. If FOCMA evokes anti-tumor immunity, it also has obvious value as a model in immunotherapy.